Employee Benefit Plans (Schedule of Net Period Benefit Cost and Other Amounts Recognized in Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplemental Executive Retirement Plan [Member]
Net period benefit cost
Service cost	$ 269	$ 232	$ 181
Interest cost	408	431	427
Recognized net actuarial loss	115	67	30
Recognized prior service cost	18	19	19
Net period benefit cost	810	749	657
Changes in funded status recognized in other comprehensive loss, before taxes
Net actuarial loss	1,334	615	361
Amortization of net unrecognized actuarial loss	(115)	(67)	(30)
Amortization of prior service cost	(18)	(19)	(19)
Total recognized in other comprehensive loss	1,201	529	312
Total recognized in net period benefit cost and other comprehensive loss	2,011	1,278	969
Other Postretirement Benefit Plan [Member]
Net period benefit cost
Service cost	70	65	60
Interest cost	148	150	143
Recognized net actuarial loss	31	5	2
Recognized prior service cost
Net period benefit cost	249	220	205
Changes in funded status recognized in other comprehensive loss, before taxes
Net actuarial loss	275	417	50
Amortization of net unrecognized actuarial loss	(31)	(5)	(2)
Amortization of prior service cost
Total recognized in other comprehensive loss	244	412	48
Total recognized in net period benefit cost and other comprehensive loss	$ 493	$ 632	$ 253